1. Field of the Invention
This invention pertains to semiconductor radiation detectors. More particularly, this invention pertains to circuits for reading the outputs from elements in a two-dimensional array of semiconductor, radiation detectors. The charge injection device (CID) technique for reading the output of such arrays is described in U.S. Pat. No. 4,079,422 and by Burke and Michon, "Charge Injection Imaging: Operating Techniques and Performances Characteristics," IEEE Journal of Solid-State Circuits, pp. 121-128, vol. SC-11, No. 1, Feb. 1976, and in the parent application referred to above.
2. Description of the Prior Art
U.S. Pat. No. 4,338,633 referred to above describes a method for "reading" the output from each element of a two-dimensional array of semiconductor, radiation detectors and integrating this output. The output of a particular element in the array is read by measuring the voltage output from it associated column conductor when the voltage on the row conductor connected to the adjacent row element is altered so as to cause the charge collected under the column electrode to transfer to the adjacent row electrode.
In the read-out procedure described in the parent application, an interval at the end of each charge collection period was used to "read out" each of the elements in the array of radiation detectors by measuring the changes in the output voltages of the column conductors as the voltage on each of the row conductors was altered. Normally the column voltage varies linearly with time during the read-out process as radiation-generated charge continues to collect under the column electrodes. In many cases, this linear variation is small compared to the discrete voltage change that occurs when charge transfer takes place. In other cases, the linear variation of column voltage cannot be ignored.